Track sander



y 1943. w; A; BALDWIN 2,324,214

TRACK SANDER Filed Oct. 5, 1942 CLfA/VOUT P/PE Immunol- WayneABaldwinGttorncgs I Patented July 13, 1943 TRACK SANDER Wayne A. Baldwin,Watertown, N. Y., assignor to The New York Air Brake Company, acorporation of New Jersey Application October 5, 1942, Serial No.460,878

7 Claims.

This invention relates to rail sanders and particularly to a finalcleanout valve which operates at the close of the sanding function toblow the sanding hose clean and reduce the risk of clogging.

With sand traps of the type claimed in the patent to Campbell No.2,243,242, issued May 27, 1941, it has been customary to use for controlpurposes a rather expensive piston operated slide valve which firstsupplies cleanout air, then sanding air, and finally cleanout air. Sucha valve is shown in that patent.

To render this type of trap available for less expensive installations,the present invention was developed. It is a relatively simple matter totime the initial cleanout blast by a well known timing valve of thediaphragm type, but such a valve will not time a final cleanout blast.

The present invention affords a second timing valve of novel type, whichstores a volume of air under pressure during sanding, and delivers thisair for cleanout purposes as sanding pressure fades out.

Thus two simple and inexpensive timing valves may be associated with oneor more traps, one valve supplying the initial, and the other valve thefinal, cleanout air. In this way installation and maintenance costs arematerially reduced. The timing cycles are precise enough for all exceptpossibly very high speed equipment.

In the drawing the single view is a diagram, partly in section, of twotraps and the controlling mechanism therefor.

Any reasonable number of adjacent traps may be controlled in unison by asingle diaphragm timing valve unit provided the storage tank for finalcleanout air be made of adequate volume. The timing valves can beconstructed as a unit with a trap, but this requires space not usuallyavailable at the location of the trap.

In the drawing the pipe I is the air supply pipe and furnishescompressed air at suitable pressure to the engineers sanding valve 2 andto the diaphragm valve unit 3 whose function is to control the operationof one or more sanding traps whose housings are indicated at 4 (twotraps being illustrated).

The valve 2 is desirably constructed according to the Campbell PatentNo. 2,222,604, issued November 26, 1940, and functions to delivercompressed air to sanding control pipe 5 to cause sanding and then tovent said pipe 5 to terminate sanding. Beyond this the special functionsof valve 2 are not here material.

Each sand trap receives sand through connection 6 from a sand box suchas the box 1. It delivers sand through throat 8 to pipe 9 whichterminates in a distensible self-clearing nozzle II. The sand does notflow through throat 8 by gravity, but is entrained by an ejector efiectwhen sanding air from pipe 12 and passage I3 is discharged by nozzle l4.The part I0 is the stirring nozzle which is fed by atmospheric air drawninto the trap by the ejector action.

Encircling nozzle [4, and slidable thereon, is sleeve IS with diaphragmthrust plate IS. The elastic diaphragm I1 is connected at its center tosleeve l5 and at its margin to housing 4. The space above the diaphragmis subject to the pressure in the cleanout pipe l8 and the space belowis open to the interior of the trap through filter plug IS.

The lower end of sleeve I5 is connected to elastic tube 2| whose upperend is connected to the body 4 as shown. A spring 22 normally holds thesleeve IS in its upper position, but when diaphragm I1 is subjected tofluid pressure and forced downward, tube 2| seals throat 8 from the sandchamber in housing 4. At such time cleanout air fiows between sleeve l5and nozzle l4 and acts to blow pipe 9 clear.

The action of the trap is more elaborately described in Patent No.2,243,242 and is not a feature of the present invention.

When pressure is developed in pipe 5 by the operation of valve 2, itacts beneath diaphragm 23, forces up stem 24 and unseats poppet valve25. This admits air at supply pressure from a branch of pipe I, throughpassage 26 to passage 21 which is in free communication with sandingpipe l2, rendering ejector nozzle [4 at once active.

Practically simultaneously diaphragm I1 is subjected to pressure andforced down, by air delivered from passage 21, through branch 28 pastseat 29 to port 3| which communicates with a branch of cleanout pipe 18.This initial cleanout fiow is limited in duration by a timing valve. Thetiming valve comprises the diaphragm 32, which acts as a valve againstseat 29, the timing chamber 33, timing choke 34 and loading spring 35with thrust plate 36.

When pressure rises in passage 21 and branch 28, diaphragm 32 is forcedup away from seat 29 because chamber 33 is then at low (atmospheric)pressure. As chamber 33 charges by flow through choke 34, a pressurewill be reached at which spring 35 will close diaphragm 32 against seat29. This ends the initial cleanout flow.

Thus, in the first phase, throat 8 receives no sand but does receive airat supply pressure from sanding pipe |2 through nozzle l4 and fromcleanout pipe 18 through the clearance between nozzle I4 and sleeve Whenthe cleanout air is cut ofi, diaphragm |1 rises and sanding starts.

To provide a cleanout cycle immediately after the termination ofsanding, a second diaphragm operated valve is provided. This functionsin two phases. The first phase is initiated by the rise of pressure insanding control line 5 and hence in passage 21. The second phase isinitiated by the fading of these pressures.

In the first phase, the diaphragm valve acts to accumulate a charge ofair. This charge ultimately attains approximately the pressure ofsupply. The volume accumulated is made such as to supply a cleanoutblast of suitable duration to all the traps which it serves. In thesecond phase, the air so stored is discharged through the cleanout lineI8.

The valve mechanism in question is mounted in housing 3 and comprises adifferential diaphragm unit made up of the large diaphragm 4|, thesmaller diaphragm 42, and connecting stem 44. The large diaphragm servesas a motor diaphragm and the smaller diaphragm 42 serves primarily as avalve coacting with the seat 43. Stem 44 has thrust plates 45 embracingthe diaphragm 4|. The lower end of the stem 44 is connected to thecenter of the diaphragm 42 by a screw and washer indicated at 46. Thespace 40 between the diaphragms is in free communication with a storagereservoir 41, of suitable volume, and also is in free communication withthe space within valve seat 43, by way of passage 48. The space beneaththe lower diaphragm 42 outside valve seat 43 is in free communicationwith the cleanout pipe l8.

Above the diaphragm 4| is a closed chamber 49 which is in freecommunication with the passage 21. The space 40 between the diaphragmsis in restricted communication with the passage 21 by way of the choke5| and the ball check valve 52 which opens to permit flow from passage21 to this space but closes against reverse flow. A spring 53 biases thediaphragm 4| and stem 44 downward so that the small diaphragm 42normally closes against the seat 43.

In the first phase, that is when sanding pressure is rising and ismaintained in passage 21, the chamber 49 immediately charges so that thespring 53 maintains the diaphragm 42 against seat 43. The space 40between the diaphragms and the storage volume 41 charge more slowly byflow through the choke 5| and valve 52. If sanding continues long enoughthe volume 41 will charge to the pressure of supply which then isestablished in the passage 21. In any event, the reservoir 41 will becharged to some extent.

When sanding is to be terminated and valve closes, the pressure inpassage 21 rapidly fades out because of flow from this passage throughthe sanding pipe l2 and nozzle I4. This entails a fall of pressure inthe chamber 49. The pressure developed in the storage volume 41 iseffective in chamber 48 between the differential diaphragms and acts tomove the stem 44 upward carrying the diaphragm 42 away from the seat 43and permitting the stored compressed air to flow from the storage volume41 through port 48 past seat 43 to the cleanout pipe I8.

This affords a final cleanout blast which forces the diaphragm H of thetraps downward to terminate the flow of sand after which the air flowblows the sand pipe 9 clear.

The cycle resembles that secured with the slide valve mechanismdescribed and claimed in the Campbell patent, above identified. It isnot quite identical, and for some purposes is inferior. Where simplicityand expense are controlling factors, the operation is sufficientlypreuse.

The particular form of control valve 2 which may be used is a matter ofchoice. Basically the function of this valve is to admit air underpressure to pipe 5 and then vent that pipe. Any control valve whichsecures this result might be substituted.

The two diaphragm valve mechanisms are shown mounted in a single housingtogether with the pilot control valve 25 and its actuating diaphragm 23.

The pilot valve 25 is desirable when the valve 2 is located at aconsiderable distance because it permits the use of a small control pipe5. Where the valve 2 is close to the traps or where the pipe 5 can bemade sufliciently large, the valve 25 can be dispensed with.

It is not necessary that the two diaphragm valves be mounted in the samehousing. In fact, valves of this type could even be mounted on thehousing 4 of the sand trap. Such an arrangement is not ordinarilypracticable because there is rarely room for the valves themselves, notto mention the volume 41.

I claim:

1. The combination of a sanding trap having a sanding air connection anda cleanout air connection; an impulse valve rendered efiective bydevelopment of pressure in the sanding air connection to deliver a timedpressure impulse therefrom to the cleanout air connection; a localreservoir; and a second valve mechanism subject to pressure in thesanding air connection and serving when the sanding connection is underpressure to charge said reservoir therefrom, and serving in response todissipation of such pressure to connect said reservoir with the cleanoutair connection.

2. The combination of a sanding trap having a sanding air connection anda cleanout air connection; a reservoir; and valve means responsive topressure in the sanding air connection, said valve means comprising,means for charging the reservoir at a restricted rate from the sandingconnection, and valve means responsive to falling pressure in thesanding connection and serving to connect said reservoir temporarilywith the cleanout connection.

3. The combination of a sanding trap having a sanding air connection anda cleanout air connection; a reservoir; and valve means responsive topressure in the sanding air connection, said valve means comprising,means for charging the reservoir at a restricted rate from the sandingconnection, timing valve means responsive to development of pressure inthe sanding connection and serving for a limited period to connect thesanding connection with the cleanout connection, and valve meansresponsive to falling pressure in the sanding connection and serving toconnect said reservoir temporarily with the cleanout connection.

4. The combination of a sanding trap having a sanding air connection anda cleanout air connection; a reservoir; means permitting restrictedcharging flow from the sanding air connection to the reservoir; and apressure-motor operated valve controlling a connection between thereservoir and the cleanout air connection, subject to the pressuredifferential between the reservoir and the sanding air connection, andarranged nection to deliver air under pressure therefrom to the cleanoutair connection; timing means for terminating such delivery; means forcharging of the reservoir from the sanding air connecto close exceptwhen reservoir pressure exceeds 5 tion; and means rendered efiective bydepletion sanding air connection pressure. of sanding connectionpressure below reservoir 5. The combination of a sanding trap havingpressure to connect the reservoir with the cleana sanding air connectionand a cleanout air conout connection. nection; a reservoir; meanspermitting restricted '7. The combination of a sanding trap havingcharging flow from the sanding air connection 10 a sanding airconnection and a cleanout air conto the reservoir; means inhibiting backflow from nection; a reservoir; means for charging the resthe reservoirto the sanding connection; and a ervoir from the sanding air connectionwhen the pressure-motor operated valve controlling a conlatter is underpressure; a valve controlling a nection between the reservoir and thecleanout connection between the reservoir and the cleanair connection,subject to the pressure differential 15 out air connection; meansbiasing said valve in between the reservoir and the sanding air conaclosing direction; and an abutment connected nection, and arranged toclose except when reserto said valve and subject to the pressurediffervoir pressure exceeds sanding air connection ential betweenreservoir pressure and pressure pressure. in the sanding air connection,the parts being 6. The combination of a sanding trap having 20 soarranged that the bias on the valve will be a sanding air connection anda cleanout air conovercome when reservoir pressure materiallyprenection; a reservoir; means responsive to the dominates. developmentof pressure in the sanding air con- WAYNE A. BALDWIN.

#460,878 w. a. Baldwin lled: Uctv5-l9l 2

